For hundreds of years, attempts have been made to protect flammable materials against fire. In recent years, various governmental agencies have adopted fire safety standards concerning many fabrics and construction materials and this trend will accelerate in the future. The increase in yearly numbers of deaths from fires has helped accelerate legislative efforts in this respect.
Increasingly, however, it has become apparent that fire-related deaths are due in only minor proportion to the actual flame of the fire itself. It is now realized that there are three dominant factors in fire-related deaths and that smoke inhalation is the most important of those factors.
The three factors which cause death by fire are:
(1) FLAME,
(2) SUFFOCATION CAUSED BY LACK OF OXYGEN, THE OXYGEN HAVING BEEN CONSUMED BY THE FIRE, AND CONCOMITANT INCREASED CARBON MONOXIDE CONCENTRATIONS, AND
(3) SUFFOCATION CAUSED BY INHALATION OF SMOKE WHICH ACTS AS A POWERFUL IRRITANT AND WHICH REDUCES THE AMOUNT OF OXYGEN AVAILABLE UPON INHALATION OF A GIVEN VOLUME OF AIR.
Of those three factors, the latter is considered the main contributor to fire-related deaths, since it has been found that only a few breaths of smoke-filled air is sufficient to incapacitate an individual. Further, lethal amounts of smoke may be generated by even small, relatively innocuous fires.
All organic-based materials will burn, given proper conditions or proportions of heat and air. In recent years, plastic materials have found increasing use and many such materials pose a potential of fire wherever they are used.
Since plastics are organic materials, it would be impossible to make them non-combustible in all situations. Many additives and modifiers have been used to decrease the rate of burning and the spread of flame; however most of the additives and modifiers so-used are organic materials themselves which will burn under proper conditions. Many inorganic materials have also been used as flame retardants, but they are effective only when used in large amounts which are detrimental to polymer properties. Accordingly, known flame-retardant additives, whether organic or inorganic, can be used in only small amounts or the physical properties of the plastic will be adversely affected.
The main cause of fire-related deaths, however, has been overlooked in the quest for better flame retardants. The problem of deaths caused by smoke-inhalation remains.
It is not surprising that smoke reduction technology has not kept pace with flame reduction technology since it has seemed apparent to those skilled in the art that a system for reducing both smoke and flame would not be feasible. It was heretofore believed that smoke propagation was due to incomplete oxidation of the volatile products of pyrolysis and that smoke reduction could be achieved only by more complete oxidation, which inherently meant more flame. Conversely, increased smoke propagation was believed to be the natural and immutable consequence of flame reduction (i.e., reduced combustion).
Accordingly, there is a great need for halogen-containing polymer material having reduced smoking characteristics, which are flame retardant, and which contain smoke and flame controlling additives in amounts insufficient to adversely affect the physical properties of the vinyl polymer.